Ring-like elements made of shape memory material such as Nitinol have been commercially used for retention of connector pins under ambient temperatures. Such Nitinol rings have also been experimentally used to release latch pins at elevated temperatures within tubular casings as disclosed for example in U.S. patent application Ser. No. 09/107,314 filed Jun. 30, 1998, the disclosure of which is incorporated herein by reference. It is therefore an important object of the present invention to provide a method of manufacturing such Nitinol rings so as to meet the installational and operational requirements of thermally responsive control of latching means used to maintain sections of casings interconnected.